1998 Johnson Evinrude "EC" 25, 35 HP 3-Cylinder Outboards Service Manual, Page 122Get this manual
Engine Temperature Check The Markal Thermomelt Stik is heat-sensitive marker that melts on contact with surface of specific temperatureOne source of Thermomelt Stiks is Stevens Instrument Company
At least two Thermomelt Stiks or OVIC Temperature Gun, PIN 772108, or digital pyrometer should be used to accurately determine the engine's operating temperatures
The Thermomelt Stik mark will appear dull and chalky when the surface marked is below the Stik's rated temperatureWhen the surface exceeds the Stik's rated temperature, the mark will appear liquid and glossyTo achieve accurate and consistent readings, engine temperature must be gauged at the top of the thermostat pocket
INotel For the following engine operating temperatures and RPM figures to be correct, the inlet water temperature must be 70 100 (21 30 Cl
Pyrometer Procedure
Twist and remove spark plug leads before changing propellers to avoid accidental starting of engine